Method of sterilizing fruit in refrigerator cars



May 19,v 1931. L. w. COLLINS 1,806,012

METHOD OF STERILIZING FRUIT IN REFRIGERATOR CARS Filed Sept. 2l. 1929 l I I I i lli l- Il ll. Il -l- `f' ,d f 1 j f (n INVENTOR L.. Wvm@ EY Y @1,1m

ATTORNEY Patented May 19, 1931 UNITE STATES v,criticus LESTER W. COLLINS, F MODESTO, CALIFORNIA., SSIGNOR TO A SUL CHEMICAL COM'.- PANY OF CALIFORNIA, 0F MODESTO, QALIFORNIA,` A CORPORATION METHOD OF STERILIZING FRUIT IN REFRIGBATOR GARS Application filed September 21, 1929; Serial No. 394,297.'-

This invention relates to the sterilization of fruit, particularly grapesbwhen they are packed in iced refrigerator cars at the start of the trip to market; My invention alsoparticularly relates to sterilizing by means of sulphur-dioxide gas.

The value of this gas for the above pur` pose has been recognized for some time, but heretofore it has been considered necessary 1o to open the Ventilating hatches of the car while sterilizing operations were in progress to prevent the sulphurdioxide burning the grapes. It has also been considered absolutely necessary to initially ldilute the gas with air from outside the car to likewise prevent burning. Retaining the ventilating hatches open, however, requires a much larger volume of gas for sterilizing than would otherwise be the case and seriously interferes with the normal circulation of the air in the cars induced by the ice packed therein. Also, initially diluting the gas requires the use of a very elaborate and eX pensive apparatus which is very diicult to use in commercial practice. Such an apparatus necessitates a mechanism mounted eX- ternally of the car and the use of a falsedoor, since a main door of the car must be left open to provide for connecting parts of the apparatus disposed both outside and inside the car. Removal of this false-door when sterilizing is completed inevitably permits a considerable quantity of the gas in the car to escape, since the removing operation and the closing of the maindoor cannot be carried out sufciently fast to prevent such escape. Y

The principal object of my invention is to accomplish that which has heretofore been considered impossible or impractical, namely, to discharge the undiluted sterilizing gas into the car in such a manner that it is not necessary to open the Ventilating hatches or doors of the car, while at the same time burning of the fruit by the sterlizing gas is positively prevented. Il am, therefore, enabled to use a much simpler apparatus which is entirely within the car and which may be instantly placed in or removed from the car upon opening the main door. The quantity of gas to properly sterilize the fruit is thus i greatly escape in the outside atmosphere.

Also, the apparatus is of such a nature that a measured supply of sterilizing gas, just sufficient for one car, may be placed in the same, so that there is positively no danger of under or over dosing the fruit, and thus careful supervision of the sterilizing operation is unnecessary.

To illustrate my method the accompanying dra-wing is presented, which shows in diagrammatic form a fragmentary longitudinal section of aloaded refrigerator car, with the sterilizingapparatus in operation.

ln carrying out my sterilizing method I use a tank l containing liquefied sulphur dioxide gas, the size of the tank being designed to hold a quantity of the liquefied gas just sulicient for one determined by experience. This tank is provided on top with a removably connected spray nozzle 2, is controlled b 'a suitable valve 3. When the gas is to be discharged the tank 1 is placed in a specially designed vessel 4 which contains water heated to a desired and relatively high temperature. This vesselmaintains the tank l upright, the nozzle 2 then facing upwardly.- By reason of the heated water in the vessel 4f the liqueed gas in the tank 1 is rapidlyv vaporized and compressed to a high pressure so that when the valve 3 is opened the sterilizing gas isl ejected upwardly from the nozzle i with considerable velocity.

While the apparatus may be merely set on the car floor 5 during the sterilizing proc- 'ess,when the space between the fruit boxes Yis suiliciently `will therefore strike the ceiling of`the car car, as has been' lessened since practically none can the discharge from which Y c ing 7 as the means with considerable force and at a high velocity, the purpose of which will be seen later. It is obvious that the nearer to the ceiling the apparatus sure in the tank l will be required to force the discharged sterilizing gas against the ceiling of the car and hence the less hazardous will be the method to the operator. To thus raise `the apparatus to the desired level I utilize the horizontal bars of the box bracupon which to support the apparatus, said bracing usually being in the transverse plane of the doors of the car or centrally of its length. Before the apparatus is set in operation the ice chambers 8 of the car are already filled with ice and a current of air therefore automatically and continuously circulates from the bottom of said chambers, along the cai` floor towards the center and up through the fruit boxes and central box bracing space, then back kto the ice chambers in the clear space above the boxes as indicated by the arrows 9.

The sterilizing gas as discharged from the nozzle 2 striking the ceiling at a high velocity, is spread out and broken up and rolls in cloudlike form along the ceiling and towards the end of the car as indicated at lO. he aircurrents in the car traveling above the fruit boxes in the direction of the ice chambers at each end carry this suspended gas with them, thus causing the gas to vtravel horizontally much further than it would otherwise do. It is obvious that the gas in traveling along the ceiling of the car towards the ice chambers is intimately co-mingled with the car air next the ceiling by the eddy currents and frictional ref sistance with the ceiling surface and thus produces an intimate gaseous mixture relatively dilute with respect to the SO2 content, and local concentrations which woulddamage the fruit are thus prevented. However, this gaseous mixture is of a considerably greater specic gravity than the air, and consequently tends to settle by gravity, thus passing downwardly through the interstices etween the, packed fruit boxes and percolates through to the -contents of the boxes, as indicated at ll, thus mixing with and displacing the airin such spaces and sterilizing all the grapes throughout the entire car.

A relatively even distribution of the gas onto the fruit in both directions from the center of the car is thus obtained. Overdosing of the grapes in the boxes nearest the center of the car adjacent to the apparatus is positively prevented by reason of the high velocity at which the sterilizing gas initially strikes the ceiling, and whichl throws the greater portion of the gas away from the glane of the adjacent boxes before it can rop.

Also the gas as it is ejected from the nozzle 2 1s in a relatively heated condition and is placed, the less presits specific gravity,

and hence its tendency to drop 1s not as great at Ythe instant it is disgle full car of fruit.

are required for the has been subjected to the the cold air currents from the ice chambers.

previously stated,` the gas tank l is of size that only sufficient liquefied gas is properly sterilize a sin- 4Only a few minutes contents of the tank l to .be discharged into the car, and after this it 1s a matter of only a few seconds to partially open the car door and withdraw the appara-tus from its readily accessible position on the central bracing.

From the above description it will be seen that I have provided a method which substantially fullls the objects of the inven tion as set forth herein and which has been in actual use on many thousands of cars of grapes during the present shipping season. Having thus described my invention what I cla-1m as new and useful and desire to secure by Letters Patent is:

l. The method of sterilizing produce in a refrigerator fcar having an air current circulating lengthwise thereof and induced frigerating means a uce in the car is belo of the car near the top by the action of the rend in which the prodw such air current, consisting in discharging an undiluted sterilizing gas into the said current whereby said gas'will be carried along by and intimately mixed with the air 2. The method of va refrigerator car in said current.

sterilizing produce 1n having a horizontally moving air current through the upper part of the car induced by the refrigerating means in the car and in which the produce in the car is below in introducing an undiluted sterilizing such current consisting gas -into the car upwardly from such a level in the car as to 'cause t he gas to flow laterally into the air current whereupon the diffusion of the gas is ac complished essentially through the movement of said current.

3. In a method refrigerator car in of treating produce in a which there exist free air currents induced by the refrigerating means and movin upwardly through the produce e same, the step and over t undiluted sterilizing initial point rents over the fruit, caused to be diffused through said re rigerator car.

4. A method of ste of movement of the of introducing gas into the airat the air curwhereby the as is rilizingproduce in a refrigerator car having an a1r current circulating thereof and induced lengthwise of the car near the top the action of the refrigerating means and in which the produce 1n said car is below such current consisting in effecting the distribution of an undiluted sterilizing gas in the said car a receptacle car by disposing within containing an amount oi gas not in excess of that necessary to efectually sterilize the produce within Such car and discharging such gas into the current of air whereby said gas will be carried along by and intimately mixed with the air 1n said current.

5. A method of st erilizing produce in a refrigerator car having air currents induced by the refrigerating means and flowing longitudinally of the car, consisting in discharging an undiluted sterilizing gas into the car in a space at the central portion thereof between piles of containers of produce and in an upward direction, and under ressure so that when discharged the gas will strike the ceiling of the car and be spread out horizontally essentially through t e movements of the air currents.

In testimony whereof I aix m signature.

LESTER W. C LLNS. 

